10. Normal-Tension Glaucoma - Management of Glaucoma Summer 2026

What is the AAO definition of normal tension glaucoma?

Form of open-angle glaucoma characterized by glaucomatous optic neuropathy in patients with IOP measurements consistently lower than 21 mmHg

What is the Glaucoma Foundation definition of normal tension glaucoma?

A condition characterized by progressive optic nerve damage and VF loss with statistically normal IOP

What is the problem with the AAO definition of normal-tension glaucoma?

21 mmHg is an arbitrary marker for "normal" IOP

NTG should be considered part of the spectrum of ___________

open-angle glaucoma (POAG)

True or False:

Normal tension glaucoma is quite prevalent

true

What is the prevalence of NTG based on the Baltimore Eye Study?

2.4% of the population; 24% of glaucoma patients had NTG

**included a lot of Black patients

What is the prevalence of NTG based on the Beaver Dam Eye Study?

2.1% of the population; 32% of glaucoma causes had IOP

A (large/small) proportion of glaucoma patients have statistically normal IOP

large

True or False:

Some of the clinical findings associated with NTG differ from those of POAG

true

So NTG and POAG have the same result overall? What is the result?

Yes, nerve death

What is the etiology of NTG & how is it different than POAG?

Non-IOP related mechanisms of glaucoma pathophysiology

Does NTG have a unique presentation from POAG?

Yes

Is the treatment of NTG any different than POAG?

Yes -- treatment consideration for NTG are different than those for POAG

There are _____, ______, and _____ theories for glaucoma

mechanical, biochemical, and vascular

If high IOP is NOT causing mechanical stress to the nerve in NTG, what may serve as a hypoxic stimulus for glaucomatous neuropathy?

reduced ocular blood flow

What is the equation for ocular perfusion pressure?

OPP = Diastolic blood pressure - IOP

Anything that diminishes _______ below certain levels can be harmful to ONH perfusion

diastolic BP

What are the ACCEPTED vascular risk factors for NTG?

Nocturnal hypotension

Sleep apnea

Vasospastic disease (migraine/Raynaud's phenomenon)

Hemodynamic crisis

Primary vascular dysfunction (PVD)

What are the SUSPECTED vascular risk factors for NTG?

Carotid artery disease

High cholesterol

Hypercoagulation disorder

Severe anemia

Cardiac arrhythmia

Blood dyscarias

What is translaminar pressure difference (TPD)?

The difference between the pressure inside the eye (IOP) and pressure behind the eye (ICP)

A normal nerve will show a _____ in IOP to ICP

balance

A glaucomatous nerve exhibits cupping as a result of what?

IOP > ICP

A swollen nerve results from what?

ICP > IOP

What is the equation for TPD?

TPD = IOP - ICP

What is the normal difference in IOP and ICP?

5 mmHg

Translaminar Pressure Difference (Pic)

Translaminar Pressure Difference (Pic)

Higher TPD (increases/decreases) risk of damage to the optic nerve

increases

True or False:

Both POAG and NTG patients had higher difference in TPD

true

As rim area declines in all forms of glaucoma, TPD is (higher/lower)

higher

With normal tension glaucoma, since IOP is normal, how do we get a reduced Ocular perfusion pressure?

-OPP = DBP - IOP

-IOP is normal

-DBP needs to be decreased in this equation

With normal tension glaucoma, since IOP is normal, how do we get an increased TPD?

-TPD = IOP - ICP

-IOP is normal

-ICP needs to be decreased

What are the clinical characteristics of NTG?

-saucer like cupping (shallow and gradual cupping)

-temporal rim thinning

-VF loss

-Drance hemorrhage

What is the likely VF defect in NTG?

deep but localized defect that is often near fixation

What is the prevalence of drance hemorrhage with NTG?

25%

What is the prevalence of drance hemorrhage in POAG?

8%

Which has higher likelihood of drance hemorrhaging?

POAG or NTG

NTG

What is saucerization?

ill defined, shallow cup

What is saucerization associated with?

overall decrease in VF sensitivity

Is saucerization more characteristics of NTG or POAG?

NTG

Healthy vs Saucerization of ONH (Pic)

Healthy vs Saucerization of ONH (Pic)

What are possible VF defects that can be seen with NTG commonly?

-nasal step

-paracentral defect

Temporal rim thinning causes VF defects near _____

fixation

What does a genetically weak lamina cribosa cause?

RGC axons within the macular zone of vulnerability zone to be susceptible to mechanical damage from relatively low IOP

________ imaging should be included in the work-up of NTG suspects

Ganglion cell layer imaging

GCA thinning will correspond to _______ VF defects

paracentral

The _____ testing pattern will complement the traditional 24-2 pattern for quantifying paracentral defects

10-2

What are the classical risk factors that increase a patient's risk of presenting with a paracentral glaucomatous defect?

-migraine

-low blood pressure

-sleep apnea

-drance hemorrhage

What is the prevalence of drance hemorrhaging in NTG?

25%

What is the prevalence of drance hemorrhaging in POAG?

8%

Which has higher likelihood of drance hemorrhaging?

POAG or NTG

NTG

With NTG, what type of VF defect is common?

Deep paracentral defect that does not involve peripheral VF points (near fixation)

What is a drance hemorrhage?

"disc hemorrhage"

What does a drance hemorrhage represent?

a nerve under stress

Which occurs first?

Damage to the axon or the drance heme

Not sure 🐓🥚

What is one of the most significant predictors of NTG glaucoma progression?

drance hemorrhage

For the 10th time, drance hemorrhaging is more common in (NTG/POAG)

NTG

What are the differential dx of NTG?

-physiological cupping

-red disease

-POAG with masked high IOP

-Intermittent angle closure

-secondary glaucoma

-non-glaucomatous optic neuropathy

What is physiological cupping?

a harmless, congenital anatomical variation where the central depression (the "cup") in the optic nerve head is naturally large

Since IOP is statistically "normal" in NTG, the initial trigger of concern about an NTG patient is __________

ONH appearance

With NTG, what must we do when viewing the ONH?

Must distinguish nerves damaged by glaucoma from nerves with physiological cupping

Large discs have _____ cups

large

Physiological cupping is _____ over time

consistent

Is the cupping of glaucoma consistent over time?

No

Is physiological cupping associated with functional vision loss or VF defects?

No

is glaucoma associated with functional vision loss or VF defects?

Yes

What is Red Disease?

OCT misinterpretation can cause clinicians to over-diagnose glaucoma

How to differentiate NTG from POAG with masked IOP?

Take multiple IOP measurements at various times of the day

When may POAG present with a masked high IOP?

-thin CCT

-treatment with a systemic beta blocker

When you suspect POAG may be present with a masked high IOP at night, what should be obtained?

Diurnal IOP measurement to get an IOP curve

Every glaucoma suspect needs _______

gonioscopy

When you suspect intermittent angle closure with narrow angles, you should get a _____ IOP

post-dilation

What are the forms of secondary glaucoma that need to be differentiated from NTG?

-PXE

-PDS

-Uveitic glaucoma

What are the causes of non-glaucomatous optic neuropathies that need to be differentiated from NTG?

-ischemic optic neuropathy

-compressive optic neuropathy

-optic neuritis

-prior traumatic optic neuropathy

Non-glaucomatous optic neuropathy OR NTG

bilateral

NTG

Non-glaucomatous optic neuropathy OR NTG

unilateral

Non-glaucomatous optic neuropathy

Non-glaucomatous optic neuropathy OR NTG

pallor > cupping

Non-glaucomatous optic neuropathy

Non-glaucomatous optic neuropathy OR NTG

cupping > pallor

NTG

Non-glaucomatous optic neuropathy OR NTG

VA decrease at the onset of disease

Non-glaucomatous optic neuropathy

Non-glaucomatous optic neuropathy OR NTG

VA decrease only in severe disease

NTG

Non-glaucomatous optic neuropathy OR NTG

dyschromatopsia

Non-glaucomatous optic neuropathy

Non-glaucomatous optic neuropathy OR NTG

VF loss will respect the vertical midline

Non-glaucomatous optic neuropathy

Non-glaucomatous optic neuropathy OR NTG

VF damage will be worse than the disc appearance

Non-glaucomatous optic neuropathy

Non-glaucomatous optic neuropathy OR NTG

Rapidly progressing VF loss of VA decrease

Non-glaucomatous optic neuropathy

Non-glaucomatous optic neuropathy OR NTG

Slowly progressing VF loss of VA decrease

NTG

What are the ancillary tests that may be helpful in detecting NTG?

-10-2 threshold VF

-GCL analysis

-fundus photos

-color vision

-corneal hysteresis

What corneal hysteresis value is considered a risk factor for conversion or progression of NTG?

What corneal hysteresis value is considered suspicious for conversion or progression of NTG?

9-9.5 mmHg

What corneal hysteresis value is considered the normal/avg value?

10 mmHg

What corneal hysteresis value is protective against conversion/progression of NTG

>11 mmHg

What were the patient characterstics for enrollment into the Collaborative Normal Tension Glaucoma Study?

-Avg IOP

What was the "treatment" in the Collaborative Normal Tension Glaucoma Study?

Subjects randomized to no treatment, or 30% reduction in IOP using CAIs only (no a2 agonists or beta blockers) or surgical treatment

What were the results of the Collaborative Normal Tension Glaucoma Study?

-65% of randomized, untreated eyes DID NOT SHOW progression

-35% of untreated eyes progressed, compared to only 12% of treated eyes

-IOP reduction is beneficial to eyes at risk of progression

What are the risk factors for NTG glaucomatous progression?

-Disc hemes

-Migraine

-Female sex

-African ancestry

Disc hemes made a patient ____X more likely more glaucomatous progression in the Collaborative Normal Tension Glaucoma Study

2.72

Migraine made a patient ____X more likely more glaucomatous progression in the Collaborative Normal Tension Glaucoma Study

2.58

Female sex made a patient ____X more likely more glaucomatous progression in the Collaborative Normal Tension Glaucoma Study

1.85

What are the confirmed NON-RISK factors from glaucomatous progression in the Collaborative Normal Tension Glaucoma Study?

-Baseline IOP

-Age

-FMHx

-Hypertension

What are the management protocols for NTG?

-Do not rush to treat

-Check for progression over time

-Check IOP numerous times at various times of the day

-Consider extra testing

Why should you NOT rush to treat NTG?

-Many patients do not progress without treatment

-Progression timeline is slow

How should you check for progression of NTG over time?

-OCT

-optic disc photos

-VFs